Effect of purified pancreatic enzymes (amylase, lipase, phospholipase A and trypsin) on the ultrastructure of the rabbit gallbladder, and upon the major constituents of bile, after 24 hours, 4 weeks and 8 weeks, when these enzymes have been injected into the gallbladder as sterile solutions. Light microscopy of the gallbladder wall, and polarizing light microscopy and biochemical analysis of gallbladder will be utilized. Effect which changes in the gallbladder wall have upon the active transport of Na plus, Cl minus and HCO minus 3, and upon its selective permeability. The unilateral non-everted gallbladder preparation of Diamond will be employed. Relation of these alterations of function to changes in micellar stability of bile and the solubilization of cholesterol. A standardized bile solution will be studied in the unilateral non-everted gallbladder preparation of Diamond. The study will also identify changes which occur in bile following incubation with specific pancreatic enzymes.